What is meant by path loss?
The difference between the effective transmitted power and the received power is called path
loss. It represents signal attenuation as a positive quantity measured in db. It may or may not
include the effects of antenna gain.
2. What is an ad hoc network?
An a...
1. What is meant by path loss?
The difference between the effective transmitted power and the received power is called path
loss. It represents signal attenuation as a positive quantity measured in db. It may or may not
include the effects of antenna gain.
2. What is an ad hoc network?
An ad hoc network is a multihop, infrastructure less network which has no centralized
server to control the communication between the nodes and resources cannot be reserved
beforehand. It is used in battlefields and military applications.
3. What are the challenging issues in ad hoc network maintenance? (M/J12 R08)
The challenging issues in ad hoc network are
a) Medium access scheme
b) Routing
c) Multicast routing
d) Transport layer protocol
e) Pricing Schemes
f) Quality of Service Provisioning
g) Self-Organization
h) Security
i) Addressing and Service Discovery
j) Energy Management
k) Scalability
l) Deployment considerations
4. What is hidden terminal problem?
Hidden terminals are nodes that are hidden (or not reachable) from the sender of a data
transmission session, but are reachable to the receiver of the session. The hidden terminal
can cause collisions at the receiver node.
5. Name some of the outdoor propagation models.
Some of the commonly used outdoor propagation models are:
i. Longley-Rice model
ii. Durkin’s model
iii. Okumura model
Prepared by A.Devasena., Asso. Prof/ Dept. of ECE Page 1
,EC2050 ― Mobile Ad hoc Networks VIII Semester ECE
6. Define – Indoor Propagation Model
Indoor propagation model is defined as the model which is used to characterize radio
propagation inside the buildings. The distance covered is much smaller.
7. List out some indoor propagation models.
Some indoor propagation models are:
i. Long –distance path loss model
ii. Ericession multiple break point model
iii. Attenuation factor model.
8. Differentiate an ad hoc network and a cellular network with respect to
a) Bandwidth usage
b) Cost effectiveness (Nov/Dec 12)
PARAMETER CELLULAR NETWORK AD HOC NETWORK
Bandwidth reservation requires
Easier to employ bandwidth
complex medium access control
reservation
Bandwidth protocols
usage Shared radio channel (more
Guaranteed bandwidth (designed
suitable for best-effort data
for voice traffic)
traffic)
Self-organization and
Cost of network maintenance is
Cost maintenance properties are built
high (backup power source,
effectiveness into the network. Hence the cost
staffing, etc.)
of network maintenance is less.
9. What is free space propagation model?
Propagation model which is used to predict received signal strength, when the line-of-sight path
is unobstructed between transmitter and receiver is called free space propagation model.
Prepared by A.Devasena., Asso. Prof/ Dept. of ECE Page 2
, EC2050 ― Mobile Ad hoc Networks VIII Semester ECE
10. Why are ad hoc networks needed? (May/June 12)
Ad hoc networking is often needed where an infrastructure network cannot be deployed
and managed. The presence of dynamic and adaptive routing protocols enables quick
formation of ad hoc networks and is suitable for emergency situations like natural disasters,
spontaneous meetings or military conflicts.
11. List the applications of ad hoc networks.
Ad hoc networks are widely used in
a. Military applications and battlefields
b. Collaborative and distributed computing
c. Emergency search and rescue operations
d. Wireless sensor and mesh networks
12. Distinguish between shadowing and reflection of signal propagation.
Shadowing Reflection
When the propagating radio wave hits an
Fading caused by the large buildings object which is very large compared to its
or other structures, that block the wavelength (such as the surface of Earth, or
direct transmission path from the tall buildings), the wave gets reflected by
transmitter to the receiver is known as that object. Reflection causes a phase shift of
shadowing. 180 degrees between the incident and
reflected rays.
13. What is scattering?
When a radio wave impinges on a rough surface, the reflected energy is spread out in all
directions. This is called scattering. It occurs when the wavelength of medium is small when
compared to wavelength of travelled wave. e.g. Foliage, lamp post, sharp edges.
14. List the transmission impediments of wireless channel. (or)
List the characteristics of wireless channels.
The characteristics of wireless channel are
1. Path loss
2. Fading
3. Interference
Prepared by A.Devasena., Asso. Prof/ Dept. of ECE Page 3
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